A transient ischaemic attack (TIA) or "mini stroke" is caused by a temporary disruption in the blood supply to part of the brain.

The disruption in blood supply results in a lack of oxygen to the brain.

This can cause sudden symptoms similar to a stroke, such as speech and visual disturbance, and numbness or weakness in the face, arms and legs.

But a TIA does not last as long as a stroke. The effects last a few minutes to a few hours and fully resolve within 24 hours.

The main symptoms of a TIA can be remembered with the word FAST:

Face – the face may have dropped on 1 side, the person may not be able to smile, or their mouth or eye may have dropped.

Arms – the person may not be able to lift both arms and keep them there because of weakness or numbness in 1 arm.

Speech – their speech may be slurred or garbled, or the person may not be able to talk at all, despite appearing to be awake; they may also have problems understanding what you're saying to them.

Time – it's time to dial 999 immediately if you see any of these signs or symptoms.

When to seek medical advice

In the early stages of a TIA, it's not possible to tell whether you're having a TIA or a full stroke.

It's important to phone 999 immediately and ask for an ambulance if you or someone else has symptoms of a TIA or stroke.

If a TIA is suspected, you should be offered aspirin to take straight away. This helps to prevent a stroke.

Even if the symptoms disappear while you're waiting for the ambulance to arrive, you should be assessed in hospital.

You should be referred to see a specialist within 24 hours of the onset of your symptoms.

A TIA is a warning sign that you may be at risk of having a full stroke in the near future, and an assessment can help doctors to determine the best way to reduce the chances of this happening.

If you think you may have had a TIA previously, but the symptoms have passed and you did not seek medical advice at the time, make an urgent appointment with a GP.

They can determine whether to refer you for a hospital assessment.

During a TIA, 1 of the blood vessels that supply your brain with oxygen-rich blood becomes blocked.

This blockage is usually caused by a blood clot that's formed elsewhere in your body and travelled to the blood vessels supplying the brain, although it can also be caused by pieces of fatty material or air bubbles.